台北地區公園之綠籬、彩葉、耐陰植物應用現況調查研究

Abstract

公園是居民休閒活動之處，具遊憩、生態與環境調節等功能，堪稱都市之肺。然台北市之鄰里公園常因植栽選種不對、苗木品質不佳與維護管理不當等因素，造成植物生長不良、植物病蟲害、甚至植物死亡等問題待探討及解決，故本研究針對台北地區之公園調查常用之綠籬、彩葉、遮陰下植物應用做現況調查，了解植栽應用現況及生長情形，以期提出建議及改善方法。 在綠籬植物應用方面：依栽植長度、使用率等結果顯示：綠籬植物應用最高的前十名，依序為黃金葉金露華(Duranta repens cv. Golden Leaves)、杜鵑(Rhododendron spp.)、矮仙丹(Ixora williamsii)、鵝掌藤(Schefflera arboricola)、黃金榕(Ficus microcarpa cv. Golden Leaves)、月橘(Murraya paniculata)、朱蕉(Cordyline fruticosa)、春不老(Ardisia squamulosa)、桂花(Osmanthus fragrans)、錫蘭葉下珠(Phyllanthus myrtifolius)等，將前十名，分為五個等級(5優良~1不良)，整體表現較佳者為鵝掌藤(3.56)、錫蘭葉下珠(3.35)與黃金葉金露華(3.32)等；表現較差者為杜鵑花(2.69)、月橘(2.83)。 在彩葉植物應用方面：依據使用頻率與應用面積等結果顯示，彩葉植物應用最高的前十名，依序為黃金葉金露華、黃金榕、亮葉朱蕉(Cordyline terminalis cv. Aichiaka)、變葉木(Codiaeum variegatum)、春不老、斑葉鵝掌藤(Schefflera arboricola cv. variegata)、紅葉鐵莧(Acalypha wilkesiana)、青紫木(Excoecaria cochichinensis)、銀紋沿階草(Ophiopogon japonicus cv. Argenteo-Vittatus)、白紋草(Chlorophytum bichetii)等，將前十名彩葉觀賞品質分為五級，整體表現較佳者為銀紋沿階草(4.53)、白紋草(4.46)、青紫木(4.36)、紅葉鐵莧(4)、黃金葉金露華(3.74)，其他級數在3─3.5級之間。 在遮蔭下植物應用方面：依據栽植面積與使用率等調查，遮蔭環境下之植物應用最高的前十名，依序為黃金葉金露華、桂花、朱蕉、春不老、杜鵑、鵝掌藤、矮仙丹、變葉木、黃邊虎尾蘭( Sansevieria trifasciata cv.’Laurentii’ ) 、 麥門冬( Liriope Spicata ) 等，將觀賞級數分為五級，表現較佳者依序排列為黃邊虎尾蘭(4.05)、麥門冬(3.7) 、矮仙丹(3.6)、春不老(3.6)、黃金葉金露華(3.55)、鵝掌藤(3.5)、桂花(3.45)、變葉木(3.45)、朱蕉(3.4)、最差為杜鵑(2.95)。 依上述調查結果及實驗得知，有下列數點建議可供提出以改善： 就綠籬方面：常見問題為帶狀綠籬有缺口、樹型不佳、樹冠空洞、枝葉稀疏、植物生長不良等情形，建議能夠針對生長勢較差的植株補植缺口、定期施肥，並定期修剪以促進分枝及整形效果，另應定期針對公園內遮陰喬木修剪以增加冠層下綠籬的光照度。杜鵑及梔子花(Gardenia jasminoides)等植物須加強病蟲害防治。其次、在遮陰環境下可選擇種植中性或較耐陰的樹種。對於如朱蕉等枝條較高的植物，可利用較低矮的植物營造層次並提高整體觀賞品質。 就彩葉方面：常見問題為葉色表現不佳、枝葉稀疏、植栽種類少及植栽組合層次不佳等情形。建議植栽能夠針對不同環境需求的植栽進行移植或改善環境以提高葉色及生長勢(如黃金露華等需光植物在強光下能有較佳的葉色，而竹芋類的植物大多需在遮陰下有較好的表現)。而春色葉類植物建議增加修剪次數，以增加枝數及新梢色彩表現。其次、由於所調查台北地區30處公園內僅有39種多年生的彩葉植物，且葉色以黃、紫、紅等色系為主，應可導入更多色系及型態之彩葉植物加以組合應用。 就遮陰下植物方面：其問題為選種錯誤、土表裸露、植栽種植間距過大等情形，如陽性木本植物因過度遮陰導致下位葉落葉嚴重、葉片退色、黃化、枝條稀疏等情形，建議修剪及施肥有助於避免枝條徒長及提高植栽生長表現。陰性草本植物因日射角度變化，使得直射光而導致葉片日燒傷害。建議植栽種植時，需依照需光度不同作區域性的種植，於遮陰收邊處，建議選用中性的植物來種植，以避免環境適應的問題。若遮陰下植栽應用，建議以較耐陰之彩葉植物以增加其色彩變化及提高視覺效果。 而就整體土壤調查得知，公園內的土壤pH值平均約在6.87 到6.93之間，尚在可接受的範圍內。土壤EC值平均約在172.9-207.8 μS/cm左右，呈現出養份不足的問題，若能加強肥培管理應能提高植物之生長表現。

A park is a place where residents can relax and exercise. It let people take a break and maintain an ecological environment. However, neighborhood parks in Taipei city are some problems such as selecting wrong plants, bad quality nursery, and improper management. These problems result in unhealthy and ill plants, and finally plants die. Therefore the objective of this research is to investigate common hedge, color-leaved plants and plant species under shading in the parks of Taipei region. To analysis current growth condition of selecting plants in the parks is to suggest and find a proper management. For application of common hedge plants in the parks according to planting length and using percentage, the most common is Duranta repens cv. Golden Leaves, and followed by Rhododendron spp., Ixora williamsii, Schefflera arboricola, Ficus microcarpa. cv. Golden Leaves, Murraya paniculata, Cordyline fruticosa, Ardisia squamulosa, Osmanthus fragrans and Phyllanthus myrtifolius. Based on five levels of ornamental quality from 5(fine) to 1(poor), the top three are Schefflera arboricola (3.56), Phyllanthus myrtifolius (3.35), and Duranta repens cv. Golden Leaves (3.32); the least two are: Rhododendron spp (2.69) and Murraya paniculata (2.83). For application of common color-leaved plants in the parks according to using percentage and planting area, the top is Duranta repens cv. Golden Leaves, and followed by Ficus microcarpa cv. Golden Leaves, Cordyline terminalis cv. Aichiaka, Codiaeum variegatum, Ardisia squamulosa, Schefflera arboricola cv. Variegata, Acalypha wilkesiana, Excoecaria cochichinensis, Ophiopogon japonicus cv. Argenteo-Vittatus , and Chlorophytum bichetii. Based on ornamental quality, the order of ranking is Ophiopogon japonicus cv. Argenteo-Vittatus (4.53), Chlorophytum bichetii (4.46), Excoecaria cochichinensis (4.36), Acalypha wilkesiana (4), Duranta repens cv. Golden Leaves (3.74), and others falls between 3 and 3.5. For application of plants under shading in the parks according to using percentage and planting area, the most common is Duranta repens cv. Golden Leaves, and followed by Osmanthus fragrans, Cordyline fruticosa, Ardisia squamulosa, Rhododendron spp, Schefflera arboricola, Ixora williamsii, Codiaeum variegatum, Sansevieria trifasciata cv.’Laurentii’ , Liriope Spicata. Based on using percentage, the high usage are Duranta repens cv. Golden Leaves, Osmanthus fragrans, Cordyline fruticosa, Ardisia squamulosa, Rhododendron spp, Schefflera arboricola, Ixora williamsii, Codiaeum variegatum ), Sansevieria trifasciata cv.’Laurentii’, and Liriope Spicata. Also,the ornamental quality from fine to poor are Sansevieria trifasciata cv.’Laurentii’(4.05), Liriope Spicata(3.7), Ixora williamsi(3.6), Ardisia squamulosa( 3.6), Duranta repens cv. Golden Leaves(3.55), Schefflera arboricola(3.5), Osmanthus fragrans(3.45), Codiaeum variegatum(3.45), Cordyline fruticosa(3.4), and the worst is Rhododendron spp (2.95). According to these results, there are some suggestions to modify: For the hedge plants, common problems are incompact banding hedges, free tree shape, hollow tree crown, sparse shoots and ill growth. First, the proper suggestion are exchanging ill growth plants, fertilizing and pruning regularly for promoting branching and maintaining the shape of tree crown. The large crown trees are regularly pruned to supply more light intensity to the hedges under trees. Cuckoo and Gardenia jasminoides should prevent from attacking of insect and disease. Second, selecting day-neutral plants and more shade tolerance plants are planted under shading environments. For the plans which have higher shoots such as Cordyline fruticosa, they are designed behind the shorter plants to increase arrangement and ornamental quality. For color-leaved plants, common problems are bad coloration of leaves, sparse shoots, a little plant species, and disorder of arrangement. The proper suggestion are to select correct plant species according to growth requirement such as Duranta repens cv. Golden Leaves has better performance under strong light intensity, and Maranta has better performance in the shading environment. Spring Color Leaf plants may increase the times of pruning to branching and coloration of new shoot. According to investigation in 30 parks in Taipei region, there are only 39 perennial color-leaved plants and mainly yellow, purple, and red leaves color. It can select more color and type of color-leaved plants. For plants under shading, these problems are selecting wrong plant species, bare soil surface and large spacing. The lower leaves of woody plants fall seriously, discoloration, chlorosis, sparse shoots because of insufficient light intensity. Pruning and fertilizing can resolve. Full sunlight results in leaf burned of herbaceous plants. Besides, at the edge of plants under shading, the neutral plants are more suitable for any environments. If using under shading, it is suggested that selecting shade tolerance of color-leaved plants can increase the variety of colors and enhance the quality of appreciation. The result of the soil analysis in the parks shows that the average of pH value ranges from 6.87 to 6.93. And the soil EC value ranges from 172.9 to 207.8 μS/cm,which means insufficient nutrients. To enhance the growth performance, it is suggested to fertilize regularly.